Today I would explain why the bottles of champagne, or cava, have a different and peculiar shape when compared to the standard bottle of wine.
What do we see when holding a bottle of sparkling wine?
The bottle is very heavy.
The bottom of the bottle is bended towards the inside.
And, if we open it, we notice a remarkable pressure output.
The shape of these bottles is not due to any trend or styling, neither it helps the stability nor facilitates serving the wine.
During the fermentation process, and specifically during the second fermentation, there is a significant increase of the pressure inside the bottle. At the end of the process, the inner pressure is estimated at 4 ATM, equivalent to the pressure of a truck tyre, in other words, a small "bomb"!. A poke at the base of a thinner bottle would be enough to cause an explosion.
To avoid possible disasters, a thicker glass with an inwards base (concave), was chosen in order to increase the glass surface and thus reduce the pressure on the walls and at the base of the bottle, improving the total resistance and redistributing the pressure to prevent an explosion.
Summarising, the design of the bottle is related to the inner pressure and the best way to withstand it. In any case, when we open a bottle of sparkling wine we must take special care, not to hurt anyone!